JANET Jackson is setting her fans up for another disappointment. Insiders say Jackson, who canceled her Sept. 29 show in Montreal because she fell “suddenly ill,” will also pull out of scheduled shows in Washington, DC, New Jersey and Atlanta this week. Get this, Since Montreal, Jackson has scrubbed 10 concerts, “all at the last minute,” said our source. “Janet should cancel all her dates now, so that fans and those working on the tour can have a heads-up.” The only future show she’s canceled so far is tomorrow’s Madison Square Garden performance, which was moved to Nov. 1. Live Nation, which is promoting her tour with LL Cool J, “has lost money,” our insider said, “because she keeps canceling after buses have been booked and preproduction is complete.” No explanation has been given. “Nobody truly knows what’s wrong with her,” our insider said. “People are saying the show is too much strain on her 42-year-old body.” Reps for Jackson and Live Nation didn’t return calls. Sources are now saying that Janet Jackson just arrived in Washington, DC. Let’s see if she performs in the nation’s capital or not.